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Chapter 13. Configuring IPv6 Networks
IPv4 space is becoming scarcer by the day.
By 2005, some estimates place the number of worldwide Internet users
at over one billion. Given the fact that many of those users will
have a cellular phone, a home computer, and possibly a computer at
work, the available IP address space becomes critically tight. China
has recently requested IP addresses for each of their students, for a
total of nearly 300 million addresses. Requests such as these, which
cannot be filled, demonstrate this shortage. When IANA initially
began allotting address space, the Internet was a small and little-
known research network. There was very little demand for addresses
and class A address space was freely allocated. However, as the size
and importance of the Internet started to grow, the number of
available addresses diminished, making obtaining a new IP difficult
and much more expensive. NAT and CIDR are two separate responses to
this scarcity. NAT is an individual solution allowing one site to
funnel its users through a single IP address. CIDR allows for a more
efficient division of network address block. Both solutions, however,
have limitations.
With new
electronic devices such as PDAs and cellular phones, which all need
IP addresses of their own, the NAT address blocks suddenly do not
seem quite as large.Researchers, realizing the potential IP
shortage, have redesigned the IPv4 protocol so that it supports
128-bits worth of address space. The selected 128-bit address space
provides 340 trillion possible addresses, an exponential increase
that we hope will provide adequate addressing into the near (and far)
future. This is, in fact, enough addresses to provide every person on
Earth with one billion addresses.Not only does IPv6 solve some of the address space logistics, it also
addresses some configuration and security issues. In this section,
we'll take a look at the current solutions available
with Linux and IPv6.
